Audit usage of StaticClass() in AssetMappingTable and AnimationAsset code

A user has pointed out that code in AssetMappingTable.cpp and AnimationAsset.cpp are using the StaticClass() method on pointers.

Because StaticClass is a static method, it relies on name hiding to return the appropriate overload. Therefore, calling StaticClass on two pointers of the same type may always result in equality (where the actual type's may be different).

This code should be checked to determine whether or not the original intent is correct, or if GetClass should be used instead.

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